1. Field of the Invention
This invention generally relates to a metallic seal for low load conditions. More specifically, the present invention relates to a metallic sealing ring for creating a seal between opposing surfaces at low load conditions.
2. Background Information
Many different types of sealing devices exist for sealing two opposing surfaces, such as opposing pipe ends in a pipe coupling joint, a pipe end and capping arrangement, and so on. Known seals include metallic sealing devices, which are commonly made of materials such as soft iron, carbon steel, stainless steel, high nickel alloy, Inconel or Nimonic alloys. To improve their sealing ability, the sealing surfaces of these known metallic seals can be coated with a deformable material, such as PTFE, gold, silver, copper, and the like.
Known metallic seals can be, for example, ring or annularly shaped, such as a metallic O-ring, and can have cross-sections of various shapes. For example, a "C" seal or spring-energized "C" seal is typically an annular seal having a "C" shaped cross-section. Known "E" seals are generally annular in configuration and have an "E" shaped cross-section. Other types of metallic seals having cross-sections which are parabolic, convoluted, Y-shaped, or omega-shaped (.OMEGA.-shaped) are also known.
Although metallic seals of the type described above generally can function suitably in certain applications, these types of metallic seals have several drawbacks. In particular, these types of seals generally require application of a relatively large load force (e.g., 100 to several thousand pounds per circumferential inch, pci) to achieve a desired seal integrity, thus making these types of seals impractical for use in environments unable to withstand a large load force. Also, the low load seals mentioned above, such as the E-seal and Y-seal, are incapable of being made to seal to high vacuum levels. Bolts or other types of clamping devices are needed to apply the large load force, which complicates the sealing arrangement. Hence, these types of seals generally will not provide a desired sealing integrity in a vacuum-type sealing arrangement in which no bolts or clamps are used. Furthermore, these types of seals generally have a low or moderate aspect ratio of height to width, thereby making them impractical for use in narrow sealing regions.
Examples of known seals are disclosed in U.S. Pat. No. 5,730,445 to Swensen et al.; U.S. Pat. No. 4,915,397 to Nicholson; U.S. Pat. No. 4,067,585 to Rode; U.S. Pat. No. 3,520,544 to Taylor; and published European Patent Application No. 692660A1 to Nicholson.
Accordingly, a continuing need exists for a seal, in particular, a metallic seal, capable of providing a reliable seal at low load conditions and which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.